Movable body apparatus, pattern formation apparatus and exposure apparatus, and device manufacturing method

ABSTRACT

On the +X and −X sides of a projection unit, a plurality of Y heads are arranged in parallel to the X-axis by a predetermined distance half or less than half the effective width of the scale, so that two heads each constantly form a pair and face a pair of Y scales. Similarly, on the +Y and −Y sides of the projection unit, a plurality of X heads are arranged in parallel to the Y-axis by the predetermined distance described above, so that two heads each constantly form a pair and face a pair of X scales. Of the pair of heads consisting of two heads which simultaneously face the scale, measurement values of a priority head is used, and when abnormality occurs in the measurement values of the priority head due to malfunction of the head, measurement values of the other head is used. Then, by using the measurement values of the two pairs of Y heads and the pair of X heads, a position of a stage within a two-dimensional plane is measured in a stable manner and with high precision.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional application claims the benefit of ProvisionalApplication No. 60/996,209 filed Nov. 6, 2007, the disclosure of whichis hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to movable body apparatuses, patternformation apparatus and exposure apparatus, and device manufacturingmethods, and more particularly, to a movable body apparatus equippedwith a movable body which substantially moves along a predeterminedplane, a pattern formation apparatus which forms a pattern on an objectmounted on a movable body, an exposure apparatus which forms a patternon an object by irradiating an energy beam, and a device manufacturingmethod which uses the exposure apparatus.

2. Description of the Background Art

Conventionally, in a lithography process for manufacturing microdevices(electron devices) such as semiconductor devices, liquid crystal displaydevices and the like, exposure apparatuses such as a projection exposureapparatus by a step-and-repeat method (a so-called stepper) and aprojection exposure apparatus by a step-and-scan method (a so-calledscanning stepper (which is also called a scanner) are mainly used.

With these types of projection exposure apparatus, the position of astage holding a substrate subject to exposure, such as for example, awafer, was generally measured using a laser interferometer. However, dueto finer patterns which accompany higher integration of semiconductordevices, requirements in performance is becoming tighter, and forexample, as for overlay error, the permissible value of the overalloverlay error has become an order of several nm, while the permissiblevalue of a position control error of the stage has also become equal toor less than a sub-nano order, and short-term variation of measurementvalues which is caused by air fluctuation which occurs due to theinfluence of temperature fluctuation and/or temperature gradient of theatmosphere on the beam path of the laser interferometer can no longer beignored.

Therefore, recently, an encoder with a high resolution which isimpervious to air fluctuation when compared with an interferometer hasbegun to gather attention, and an invention related to an exposureapparatus which uses the encoder in position measurement of a waferstage and the like has been proposed (refer to, for example, thepamphlet of International Publication 2007/097379 and the like).

In the exposure apparatus and the like disclosed in the pamphlet ofInternational Publication 2007/097379, position measurement of a waferstage and the like is performed, using a plurality of encoder heads.However, when position measurement of a wafer stage and the like isperformed using a plurality of encoder heads, malfunction of eachencoder head, such as, for example, a mechanical failure and the likemay cause an abnormality in the output of the encoder heads. Meanwhile,in order to achieve a highly precise exposure even in such a case, beingable to measure the position of the wafer stage continuously with highprecision is required.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is provideda first movable body apparatus including a movable body whichsubstantially moves along a predetermined plane, the apparatuscomprising: a scale which is arranged at one of the movable body and theoutside of the movable body, with a first direction within a planeparallel to the predetermined plane serving as a longitudinal direction,and having a grating section that has a predetermined width in a seconddirection orthogonal to the first direction; and a measurement devicewhich measures positional information of the movable body in a periodicdirection of the grating section at a plurality of measurement pointsplaced on the scale, whereby the placement of the plurality ofmeasurement points is decided so that of the plurality of measurementpoints, n points (wherein, n is an integer of two or more) or more arepositioned within the predetermined width on the scale, and when themovable body is at a predetermined position, n+1 or more of theplurality of measurement points are positioned to be within thepredetermined width on the scale.

According to this device, of the plurality of measurement points thatthe measurement device has, n points (wherein, n is an integer of two ormore) or more are positioned within the predetermined width on thescale, and when the movable body is at a predetermined position, n+1points or more are positioned within the predetermined width on thescale. Therefore, it becomes possible to measure positional informationof the movable body in the periodic direction of the grating sectionwhich a scale has in at least one measurement point. Accordingly, evenif abnormality occurs in a part of the measurement of n pointspositioned within the predetermined width on the scale or n+1 pointswhen the movable body is at the predetermined position, it becomespossible to measure the positional information of the movable body inthe periodic direction of the grating section which the scale has,unfailingly, with the remaining measurement points.

According to a second aspect of the present invention, there is provideda second movable body apparatus including a movable body whichsubstantially moves along a predetermined plane, the apparatuscomprising: a scale which is arranged at one of the movable body and theoutside of the movable body, with a first direction within a planeparallel to the predetermined plane serving as a longitudinal direction,and having a grating section that has a predetermined width in a seconddirection orthogonal to the first direction; and a measurement devicewhich measures positional information of the movable body in a periodicdirection of the grating section at a plurality of measurement pointsplaced on the scale, whereby the measurement device has a plurality ofhead sets including a first head which irradiates a measurement beam ona first measurement point and a second head which irradiates ameasurement beam on the first measurement point or in its vicinity.

According to this device, the measurement device has a plurality of headsets including a first head which irradiates a measurement beam on afirst measurement point of the plurality of measurement points that themeasurement device has, and a second head which irradiates a measurementbeam on the first measurement point or in its vicinity. Therefore, ofthe first head and the second head included in the head set, even itabnormality occurs in one of the heads, because the other head can beused, the head set stably irradiates measurement beams on the scale andmeasures the positional information of the movable body in the periodicdirection of the grating section which the scale has. Accordingly, byusing the measurement device which has the plurality of head sets, itbecomes possible to unfailingly measure the positional information ofthe movable body in the periodic direction of the grating section whichthe scale has.

According to a third aspect of the present invention, there is provideda third movable body apparatus including a movable body whichsubstantially moves along a predetermined plane, the apparatuscomprising: a measurement device which measures positional informationof the movable body a direction of one degree of freedom in thepredetermined plane, at a plurality of measurement points placed in amovement range or the movable body, whereby the measurement device has aplurality of heads which generate measurement information by irradiatinga measurement beam on at least one of the plurality of measurementpoints when the movable body is located at a predetermined position.

According to this device, the measurement device has a plurality ofheads which generate measurement information by irradiating ameasurement beam on at least one of the plurality of measurement pointswhen the movable body is located at a predetermined position. Therefore,it becomes possible to measure the positional information of the movablebody in a direction off one degree of freedom within the predeterminedplane, using at least one head. Accordingly, even if abnormality occursin a part of the plurality of heads, it becomes possible to measure thepositional information of the movable body unfailingly in a direction ofone degree of freedom within the predetermined plane, using another headin the remaining heads.

According to a fourth aspect of the present invention, there is provideda pattern formation apparatus that forms a pattern on an object, theapparatus comprising: a patterning device which forms a pattern on theobject, and the movable body apparatus according to the presentinvention (to be precise, any one of the first, second, or, thirdmovable body apparatus) in which the object is mounted on the movablebody.

According to this apparatus, a pattern is generated by the patterningdevice on the object, which is on a movable body that configures a partof the movable body apparatus of the present invention and canunfailingly measure the positional information in the measurementdirection. Accordingly, it becomes possible to form a pattern on theobject with good precision.

According to a fifth aspect of the present invention, there is providedan exposure apparatus that forms a pattern on an object by irradiatingan energy beam, the apparatus comprising: a patterning device thatirradiates the energy beam on the object; the movable body apparatusaccording to the present invention in which the object is mounted on themovable body, and a drive device which drives the movable body to makethe object relatively move with respect to the energy beam.

According to this apparatus, to make the object relatively move withrespect to the energy beam irradiated on the object from the patterningdevice, the drive device drives the movable body on which the object ismounted with good precision. Accordingly, it becomes possible to form apattern on the object with good precision by scanning exposure.

According to a sixth aspect of the present invention, there is provideda device manufacturing method which uses the exposure apparatusaccording to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a view schematically showing the configuration of an exposureapparatus related to an embodiment;

FIG. 2A is a planar view showing a wafer stage, and FIG. 2B is a planarview showing a measurement stage;

FIG. 3 is a view used to explain a placement of measurement axes of aninterferometer system of the exposure apparatus in FIG. 1, and is aplanar view of a stage device is, partially omitted;

FIG. 4 is a view showing a placement of various measurement systemswhich the exposure apparatus in FIG. 1 is equipped with;

FIG. 5 is a view showing a placement of an encoder head (an X head and aY head) and an alignment system;

FIG. 6 is a view showing a placement of a Z head and a multipoint AFsystem;

FIG. 7 is a block diagram showing a main configuration of a controlsystem of the exposure apparatus in FIG. 1;

FIGS. 8A and 8B are views used to describe position measurement of awafer table within an XY plane by a plurality of encoders, and aswitching of heads;

FIGS. 9A and 9B are views used to explain a baseline measurementoperation of a secondary alignment system performed at the beginning ofa lot;

FIGS. 10A and 10B are views used to explain a first and second modifiedexample of the encoder system, respectively;

FIGS. 11A and 11B are views used to explain a third and fourth modifiedexample of the encoder system, respectively; and

FIG. 12 is a view used to explain other modified examples of the encodersystem.

DESCRIPTION OF THE EMBODIMENTS

An embodiment of the present invention will be described below, withreference to FIGS. 1 to 9B.

FIG. 1 shows a schematic configuration of an exposure apparatus 100 inthe embodiment. Exposure apparatus 100 is a projection exposureapparatus by the step-and-scan method, or a so-called scanner. Asdiscussed later on, in the embodiment, a projection optical system PL isarranged, and in the description below, a direction parallel to anoptical axis AX of projection optical system PL will be described as theZ-axis direction, a direction within a plane orthogonal to the Z-axisdirection in which a reticle and a wafer are relatively scanned will bedescribed as the Y-axis direction, a direction orthogonal to the Z-axisand the Y-axis will be described as the X-axis direction, and rotational(inclination) directions around the X-axis, the Y-axis, and the Z-axiswill be described as θx, θy, and θz directions, respectively.

Exposure apparatus 100 is equipped with an illumination system 10, areticle stage RST, a projection unit PU, a stage device 50 having awafer stage WST and a measurement stage MST, and a control system ofthese parts. Although a part of the configuration is different such asthe configuration of the encoder system which will be described lateron, as a whole, exposure apparatus 100 is configured similar to theexposure apparatus disclosed in the pamphlet of InternationalPublication No 2007/097379 (and the corresponding U.S. PatentApplication Publication No. 2008/0088843) previously described.Accordingly, in the description below, the explanation given for eachcomponent will be simplified, except when especially necessary.Incidentally, in FIG. 1, a wafer W is mounted on wafer stage WST.

Illumination system 10 includes a light source, an illuminanceuniformity optical system, which includes an optical integrator and thelike, an illumination optical system that has a reticle blind and thelike (none of which are shown), as is disclosed in, for example, U.S.Patent Application Publication No. 2003/0025890 and the like.Illumination system 10 illuminates a slit-shaped illumination area IAR,which is set on reticle R with a reticle blind (a masking system), by anillumination light (exposure light) IL with a substantially uniformilluminance. In this case, as illumination light IL, for example, an ArFexcimer laser beam (wavelength 193 nm) is used.

On reticle stage RST, reticle R on which a circuit pattern or the likeis formed on its pattern surface (the lower surface in FIG. 1) is fixed,for example, by vacuum chucking. Reticle stage RST is finely drivablewithin an XY plane, for example, by a reticle stage drive section 11(not shown in FIG. 1, refer to FIG. 7) that includes a linear motor orthe like, and reticle stage RST is also drivable in a scanning direction(in this case, the Y-axis direction, which is the lateral direction ofthe page surface in FIG. 1) at a predetermined scanning speed.

The positional information (including rotation information in the θzdirection) of reticle stage RST in the XY plane (movement plane) isconstantly detected, for example, at a resolution of around 0.25 nm by areticle laser interferometer (hereinafter referred to as a “reticleinterferometer”) 116, via a movable mirror 15 (the mirrors actuallyarranged are a Y movable mirror (or a retro reflector) that has areflection surface which is orthogonal to the Y-axis direction and an Xmovable mirror that has a reflection surface orthogonal to the X-axisdirection). The measurement values of reticle interferometer 116 aresent to a main controller 20 (not shown in FIG. 1, refer to FIG. 7).

Projection unit PU is placed below reticle stage RST in FIG. 1.Projection unit PU includes a barrel 40, and projection optical systemPL that has a plurality of optical elements which are held in apredetermined positional relation inside barrel 40. As projectionoptical system PL, for example, a dioptric system is used, consisting ofa plurality of lenses (lens elements) that is disposed along an opticalaxis AX, which is parallel to the Z-axis direction. Projection opticalsystem PL is, for example, a both-side telecentric dioptric system thathas a predetermined projection magnification (such as one-quarter,one-fifth, or one-eighth times). Therefore, when illumination light ILfrom illumination system 10 illuminates illumination area IAR,illumination light IL that has passed through reticle R which is placedso that its pattern surface substantially coincides with a first plane(an object plane) of projection optical system PL forms a reduced imageof the circuit pattern (a reduced image of a part of the circuitpattern) of reticle R formed within illumination area IAR, viaprojection optical system PL (projection unit PU), in an area(hereinafter, also referred to as an exposure area) IA conjugate toillumination area IAR on wafer W whose surface is coated with a resist(a sensitive agent) and is placed on a second plane (an image plane)side of projection optical system PL. And by reticle stage RST and waferstage WST being synchronously driven, reticle R is relatively moved inthe scanning direction (the Y-axis direction) with respect toillumination area IAR (illumination light IL) while wafer W isrelatively moved in the scanning direction (the Y-axis direction) withrespect to exposure area IA (illumination light IL), thus scanningexposure of a shot area (divided area) on wafer W is performed, and thepattern of reticle R is transferred onto the shot area. That is, in theembodiment, the pattern is generated on wafer W according toillumination system 10, reticle R, and projection optical system PL, andthen by the exposure of the sensitive layer (resist layer) on wafer Wwith illumination light IL, the pattern is formed on wafer W.

In exposure apparatus 100 of the embodiment, a local liquid immersiondevice 8 is installed to perform exposure by a liquid immersion method.Local liquid immersion device 8 includes a liquid supply device 5, aliquid recovery device 6 (both of which are not shown in FIG. 1, referto FIG. 7), a liquid supply pipe 31A, a liquid recovery pipe 31B, anozzle unit 32 and the like. As shown in FIG. 1, nozzle unit 32 issupported in a suspended state by a mainframe (not shown) holdingprojection unit PU, so that the periphery of the lower end portion ofbarrel 40 that holds an optical element closest to the image plane side(the wafer W side) constituting projection optical system PL, in thiscase, a lens (hereinafter also referred to as a tip lens) 191, isenclosed. In the embodiment, as shown in FIG. 1, nozzle unit 32 is setso that its lower end surface is on a substantially flush surface withthe lower end surface of tip lens 191. Further, nozzle unit 32 isequipped with a supply opening and a recovery opening of liquid Lq, alower surface to which wafer W is placed facing and at which therecovery opening is arranged, and a supply flow channel and a recoveryflow channel that are connected to a liquid supply pipe 31A and a liquidrecovery pipe 31B respectively. Liquid supply pipe 31A and liquidrecovery pipe 31B are slanted by around 45 degrees relative to an X-axisdirection and Y-axis direction in a planar view (when viewed from above)as shown in FIG. 4, and are placed symmetric to a straight line (areference axis) LV which passes through the center (optical axis AX ofprojection optical system PL, coinciding with the center of exposurearea IA previously described in the embodiment) of projection unit PUand is also parallel to the Y-axis.

Liquid supply pipe 31A connects to liquid supply device 5 (not shown inFIG. 1, refer to FIG. 7), and liquid recovery pipe 31B connects toliquid recovery device 6 (not shown in FIG. 1, refer to FIG. 7). In thiscase, in liquid supply device 5, a tank to store the liquid, acompression pump, a temperature controller, a valve for controlling theflow amount of the liquid, and the like are equipped. In liquid recoverydevice 6, a tank to store the liquid which has been recovered, a suctionpump, a valve for controlling the flow amount of the liquid, and thelike are equipped.

Main controller 20 controls liquid supply device 5 (refer to FIG. 7),and supplies liquid between tip lens 191 and wafer W via liquid supplypipe 31A, as well as control liquid recovery device 6 (refer to FIG. 7),and recovers liquid from between tip lens 191 and wafer W via liquidrecovery pipe 31B. During the operations, main controller 20 controlsliquid supply device 5 and liquid recovery device 6 so that the quantityof liquid supplied constantly equals the quantity of water which hasbeen recovered. Accordingly, in the space between tip lens 191 and waferW, a constant quantity of liquid Lq (refer to FIG. 1) is held constantlyreplaced, and by this, a liquid immersion area 14 (for example, refer toFIG. 8A) is formed. Incidentally, in the case measurement stage MSTwhich will be described later on is positioned below projection unit PU,liquid immersion area 14 can be formed similarly in the space betweentip lens 191 and a measurement table described later on.

In the embodiment, as the liquid described above, pure water(hereinafter, it will simply be referred to as “water” besides the casewhen specifying is necessary) that transmits the ArF excimer laser light(light with a wavelength of 193 mm) is to be used. Incidentally,refractive index n of the water with respect to the ArF excimer laserlight is around 1.44. In the water the wavelength of illumination lightIL is 193 nm×1/n, shorted to around 134 nm.

As shown in FIG. 1, stage device 50 is equipped with a wafer stage WSTand a measurement stage MST placed above a base board 12, a measurementsystem 200 (refer to FIG. 7) which measures positional information ofthe stages WST and MST, a stage drive system 124 (refer to FIG. 7) whichdrives stages WST and MST and the like. Measurement system 200 includesan interferometer system 118, an encoder system 150, and a surfaceposition measurement system 190 as shown in FIG. 7. Incidentally,details on interferometer system 118, encoder system 150 and the likewill be described later in the description.

Wafer stage WST and measurement stage MST are supported above base board12, via a clearance of around several μm by a plurality of noncontactbearings (not shown) fixed to each of the bottom surfaces, such as, forexample, air pads. Further, stages WST and MST are drivableindependently within the XY plane, by stage drive system 124 (refer toFIG. 7) which includes a linear motor and the like.

Wafer stage WST includes a stage main section 91, and a wafer table WTBthat is mounted on stage main section 91. Wafer table WTB and stage mainsection 91 are configured drivable in directions of six degrees offreedom (X, Y, Z, θx, θy, and θz) with respect to base board 12 by adrive system including a linear motor and a Z leveling mechanism(including a voice coil motor and the like).

In the center of the upper surface of wafer table WTB, a wafer holder(not shown) is arranged which holds wafer W by vacuum suction or thelike. On the outer side of the wafer holder (mounting area of thewafer), as shown in FIG. 2A, a plate (a liquid repellent plate) 28 isarranged that has a circular opening one size larger than the waferholder formed in the center, and also has a rectangular outer shape(contour). A liquid repellent treatment against liquid Lq is applied tothe surface of plate 28 (a liquid repellent surface is formed).Incidentally, plate 28 is installed on the wafer table WTB uppersurface, so that its entire surface or a part of the surface becomesflush with the surface of wafer W.

Plate 28 has a first liquid repellent area 28 a having a rectangularouter shape (contour) with the circular opening described above formedin the center, and a second liquid repellent area 28 b having arectangular frame (loop) shape placed around the first liquid repellentarea. Incidentally, in the embodiment, because water is used as liquidLq as is previously described, hereinafter, the first liquid repellentarea 28 a and the second liquid repellent area 28 b will also bereferred to as a first water repellent plate 28 a and a second waterrepellent plate 28 b.

On an end on the +Y side of the first water repellent plate 28 a, ameasurement plate 30 is arranged. On measurement plate 30, a fiducialmark FM is arranged in the center, and a pair of aerial imagemeasurement slit patterns (slit-shaped measurement patterns) SL isarranged with the mark in between. And, in correspondence with eachaerial image measurement slit pattern SL, a light-transmitting system(not shown) which guides illumination light IL passing through the slitpatterns outside wafer stage WST (a photodetection system arranged inmeasurement stage MST which will be described later on) is arranged.

On second liquid repellent area 28 b, scales for an encoder system (tobe described later) are formed. More specifically, in areas on one sideand the other side in the X-axis direction of the second water repellentplate 28 b (both sides in the horizontal direction in FIG. 2A), Y scales39Y₁ and 39Y₂ are formed, respectively. Y scales 39Y₁ and 39Y₂ are eachcomposed of a reflective grating (for example, a diffraction grating)having a periodic direction in the Y-axis direction in which grid lines38 having the longitudinal direction in the X-axis direction are formedin a predetermined pitch along a direction parallel to the Y-axis (theY-axis direction). Similarly, in areas on one side and the other side inthe Y-axis direction of the second water repellent plate 28 b (bothsides in the vertical direction in FIG. 2A), X scales 39X₁ and 39X₂ areformed, respectively, in a state where the scales are placed between Yscales 39Y₁ and 39Y₂. X scales 39X₁ and 39X₂ are each composed of areflective grating (for example, a diffraction grating) having aperiodic direction in the X-axis direction in which grid lines 37 havingthe longitudinal direction in the Y-axis direction are formed in apredetermined pitch along a direction parallel to the X-axis (the X-axisdirection). The pitch of grid lines 37 and 38, for example, is set to 1μm. Incidentally, in FIG. 2A, the pitch of the gratings is illustratedlarger than the actual pitch for the sake of convenience. The same istrue also in other drawings.

Incidentally, in order to protect the diffraction grating, it is alsoeffective to cover the grating with a glass plate with low thermalexpansion that has water repellency. In this case, as the glass plate, aplate whose thickness is the same level as the wafer, such as forexample, a plate 1 mm thick, can be used, and the plate is set on theupper surface of wafer table WTB so that the surface of the glass platebecomes the same height (surface position) as the wafer surface.

Further, to the −Y end surface and the −X end surface of wafer tableWTB, mirror-polishing is applied, respectively, and as shown in FIG. 2A,reflection surfaces 17 a and 17 b are formed for interferometer system118 which will be described later in the description.

Measurement stage MST includes a stage main section 92 driven in the XYplane by a linear motor and the like (not shown), and a measurementtable MTB mounted on stage main section 92, as shown in FIG. 1.Measurement stage MST is configured drivable in at least directions ofthree degrees of freedom (X, Y, and θz) with respect to base board 12 bya drive system (not shown).

Incidentally, in FIG. 7, the drive system of wafer stage WST and thedrive system of measurement stage MST are included and are shown asstage drive system 124.

Various measurement members are arranged at measurement table MTB (andstage main section 92). As such measurement members, for example, asshown in FIG. 2B, members such as an uneven illuminance measuring sensor94 that has a pinhole-shaped light-receiving section which receivesillumination light IL on an image plane of projection optical system PL,an aerial image measuring instrument 96 that measures an aerial image(projected image) of a pattern projected by projection optical systemPL, a wavefront aberration measuring instrument 98 by the Shack-Hartmanmethod that is disclosed in, for example, the pamphlet of InternationalPublication No. 2003/065428, an illuminance monitor (not shown) and thelike are employed. Further, in stage main section 92, a pair ofphotodetection systems (not shown) is arranged in a placement facing thepair of light-transmitting systems (not shown) previously described. Inthe embodiment, in a state where wafer stage WST and measurement stageMST are in proximity within a predetermined distance in the Y-axisdirection (including a contact state), illumination lights IL that hasbeen transmitted through each aerial image measurement slit pattern SLof measurement plate 30 on wafer stage WST are guided by eachlight-transmitting system (not shown) and are received bylight-receiving elements of each photodetection system (not shown)within measurement stage MST.

On the −Y side end surface of measurement table MTB, a fiducial bar(hereinafter, shortly referred to as an “FD bar”) 46 is arrangedextending in the X-axis direction, as shown in FIG. 2B. In the vicinityof the end portions on one side and the other side in the longitudinaldirection of FD bar 46, a reference grating (for example, a diffractiongrating) 52 whose periodic direction is the Y-axis direction isrespectively formed, placed symmetric to a center line CL. Further, onthe upper surface of FD bar 46, a plurality of reference marks M isformed. As each of reference marks M, a two-dimensional mark having asize that can be detected by a primary alignment system and secondaryalignment systems (to be described later) is used. Incidentally, thesurface of FD bar 46 and the surface of measurement table MTB are alsocovered with a liquid repellent film (water repellent film).

On the +Y end surface and the −X end surface of measurement table MTB,reflection surfaces 19 a and 19 b are formed similar to wafer table WTBas is previously described (refer to FIG. 2B).

In exposure apparatus 100 of the embodiment, a primary alignment systemAL₁ having a detection center at a position spaced apart from opticalaxis AX of projection optical system PL at a predetermined distance onthe −Y side is placed on reference axis LV previously described as shownin FIGS. 4 and 5. Primary alignment system AL1 is fixed by the lowersurface of a (not shown) mainframe. On one side and the other side inthe X-axis direction with primary alignment system AL1 in between,secondary alignment systems AL2 ₁ and AL2 ₂, and AL2 ₃ and AL2 ₄ whosedetection centers are substantially symmetrically placed with respect tostraight line LV are severally arranged. Secondary alignment systems AL2₁ to AL2 ₄ are fixed via a movable support member to the lower surfaceof the mainframe (not shown), and by drive mechanisms 60 ₁ to 60 ₄(refer to FIG. 7), their detection areas (or detection center) can bedriven independently in the X-axis direction. Accordingly, the relativepositions of the detection areas of primary alignment system AL1 andsecondary alignment systems AL2 ₁, AL2 ₂, AL2 ₃ and AL2 ₄ are adjustablein the X-axis direction. Incidentally, a straight line (a referenceaxis) LA which passes through the detection center of primary alignmentsystem AL1 and is parallel to the X-axis shown in FIG. 4 and the likecoincides with the optical axis of a measurement beam B6 frominterferometer 127 previously described.

In the embodiment, as each of alignment systems AL1 and AL2 ₁ to AL2 ₄for example, an FIA (Field Image Alignment) system by an imageprocessing method is used. The imaging signals from each of alignmentsystems AL1 and AL2 ₁ to AL2 ₄ are supplied to main controller 20, via asignal processing system (not shown).

Incidentally, each of the alignment systems described above is notlimited to the FIA system, and an alignment sensor, which irradiates acoherent detection light to a subject mark and detects a scattered lightor a diffracted light generated from the subject mark or makes twodiffracted lights (for example, diffracted lights of the same order ordiffracted lights being diffracted in the same direction) generated fromthe subject mark interfere and detects an interference light, cannaturally be used alone or in combination as needed.

Next, a configuration and the like of interferometer system 118 (referto FIG. 7), which measures the positional information of wafer stage WSTand measurement stage MST, will be described.

Interferometer system 118 includes a Y interferometer 16, Xinterferometers 126, 127, and 128, and Z interferometers 43A and 43B forposition measurement of wafer stage WST, and a Y interferometer 18 andan X interferometer 130 for position measurement of measurement stageMST, as shown in FIG. 3. Y interferometer 16 and the three Xinterferometers 126, 127, and 128 each irradiate interferometer beams(measurement beams) B4 (B4 ₁, B4 ₂), B5 (B5 ₁, a B5 ₂), B6, and B7 onreflection surfaces 17 a and 17 b of wafer table WTB. And Yinterferometer 16 and the three X interferometers 126, 127, and 128 eachreceive the reflected lights, and measure the positional information ofwafer stage WST in the XY plane, and supply the positional informationwhich has been measured to main controller 20.

Incidentally, for example, X interferometer 126 irradiates at leastthree measurement beams parallel to the X-axis including a pair ofmeasurement beams B5 ₁ and B5 ₂ which passes through optical axis (inthe embodiment, also coinciding with the center of exposure area IApreviously described) AX of projection optical system PL and issymmetric about a straight line (reference axis LH (refer to FIGS. 4, 5and the like)) parallel to the X-axis. Further, Y interferometer 16irradiates at least three measurement beams parallel to the Y-axisincluding a pair of measurement beams B4 ₁ and B4 ₂ which is symmetricabout reference axis LV previously described on reflection surface 17 aand a movable mirror 41 (to be described later on). As described, in theembodiment, as each interferometer, a multiaxial interferometer which aplurality of measurement axis is used, with an exception for a part ofthe interferometers (for example, interferometer 128). Therefore, inaddition to the X, Y positions of wafer table WTB (wafer stage WST),main controller 20 can also compute rotation information (that is,pitching amount) in the θx direction, rotation information (that is,rolling amount) in the θy direction, and rotation information (that is,yawing amount) in the θz direction, based on the measurement results ofY interferometer 16 and either X interferometers 126 or 127.

Further, as shown in FIG. 1, movable mirror 41 having a concave-shapedreflection surface is attached to the side surface on the −Y side ofstage main section 91. As it can be seen from FIG. 2A, movable mirror 41is designed so that the length in the X-axis direction is longer thanreflection surface 17 a of wafer table WTB.

A pair of Z interferometers 43A and 43B are arranged (refer to FIGS. 1and 3), facing movable mirror 41. Z interferometers 43A and 43Birradiate two measurement beams B1 and B2, respectively, on fixedmirrors 47A and 47B, which are fixed, for example, on a frame (notshown) supporting projection unit PU, via movable mirror 41. And byreceiving each reflected light, Z interferometers 43A and 43B measurethe optical path length of measurement beams B1 and B2. And from theresults, main controller 20 computes the position of wafer stage WST infour degrees of freedom (Y, Z, θy, and θz) directions.

In the embodiment, position information within the XY plane (includingthe rotation information in the θz direction) of wafer stage WST (wafertable WTB) is mainly measured by an encoder system (to be describedlater). Interferometer system 118 is used when wafer stage WST ispositioned outside the measurement area (for example, near unloadingposition UP and loading position LP as shown in the drawings such asFIG. 4) of the encoder system. Further, interferometer system 118 isused secondarily when correcting (calibrating) a long-term variation(for example, temporal deformation of the scale) of the measurementresults of the encoder system and the like. As a matter of course, allpositional information of wafer stage WST (wafer table WTB) can bemeasured using both interferometer system 118 and the encoder systemtogether.

Y interferometer 18 and X interferometer 130 of interferometer system118 irradiate interferometer beams (measurement beams) on reflectionsurfaces 19 a and 19 b of measurement table MTB as shown in FIG. 3, andmeasure the positional information of measurement stage MST (including,for example, at least the positional information in the X-axis and theY-axis directions and the rotation information in the θz direction) byreceiving the respective reflected lights, and supply the measurementresults to main controller 20.

Next, the structure and the like of encoder system 150 (refer to FIG. 7)which measures the positional information of wafer stage WST in the XYplane (including rotation information in the θz direction) will bedescribed.

In exposure apparatus 100 of the embodiment, as shown in FIG. 4, fourhead units 62A to 62D are placed in a state extending from nozzle unit32 in four directions. These head units 62A to 62D are fixed to themainframe (not shown) holding projection unit UP in a suspended state,via a support member.

Head units 62A and 62C are equipped with a plurality of (nine, in thiscase) Y heads 65 ₁ to 65 ₉ and 64 ₁ to 64 ₉, as shown in FIG. 5,respectively. In detail, head units 62A and 62C are equipped with aplurality of (seven, in this case) Y heads 65 ₃ to 65 ₉ and 64 ₁ to 64 ₇placed at a distance WD on reference axis LH previously described,respectively, and a plurality of (two, in this case) Y heads 65 ₁ and 65₂, and 64 ₈ and 64 ₉ placed at distance WD a predetermined distance awayfrom reference axis LH in the −Y direction on the −Y side of nozzle unit32 in parallel with reference axis LH, respectively. Incidentally, thedistance between Y heads 65 ₂ and 65 ₃ and Y heads 64 ₇ and 64 ₈ in theX-axis direction is also set to WD. Hereinafter, Y heads 65 ₁ to 65 ₉and 64 ₁ to 64 ₉ will also be described as Y heads 65 and 64,respectively, as necessary.

Head unit 62A constitutes a multiple-lens (nine-lens, in this case) Ylinear encoder (hereinafter, shortly referred to as a “Y encoder” or an“encoder” as appropriate) 70A (refer to FIG. 7) that measures theposition of wafer stage WST (wafer table WTB) in the Y-axis direction (Yposition), using Y scale 39Y₁ previously described. Similarly, head unit62C constitutes a multiple-lens (nine-lens, in this case) Y linearencoder 70C (refer to FIG. 7) that measures the Y position of waferstage WST (wafer table WTB) using Y scale 39Y₂ described above. In thiscase, distance WD in the X-axis direction of the nine Y heads 64 and 65(to be more accurate, the irradiation points of the measurement beamsgenerated by Y heads 65 and 64 on the scale) that head units 62A and 62Care each equipped with, is set slightly narrower than the width (to bemore precise, the length of grid line 38) of Y scales 39Y₁ and 39Y₂ inthe X-axis direction. Accordingly, of each nine Y heads 65 and 64, atleast two heads each constantly face the corresponding Y scales 39Y₁ and39Y₂ at the time of the exposure. More specifically, of the measurementbeams which each nine Y heads 65 and 64 generate, at least twomeasurement beams each can be irradiated on the corresponding Y scales39Y₁ and 39Y₂.

As shown in FIG. 5, head unit 62B is placed on the +Y side of nozzleunit 32 (projection unit PU), and is equipped with a plurality of, inthis case, seven X heads 66 ₈ to 66 ₁₄ that are placed on reference axisLV previously described along Y-axis direction at distance WD. Further,head unit 62D is placed on the −Y side of primary alignment system AL1,on the opposite side of head unit 62B via nozzle unit 32 (projectionunit PU), and is equipped with a plurality of, in this case, seven Xheads 66 ₁ to 66 ₇ that are placed on reference axis LV at distance WD.Hereinafter, X heads 66 ₁ to 66 ₁₄ will also be described as X heads 66,as necessary.

Head unit 62B constitutes a multiple-lens (seven-lens, in this case) Xlinear encoder (hereinafter, shortly referred to as an “X encoder” or an“encoder” as needed) 70B (refer to FIG. 7) that measures the position inthe X-axis direction (the X-position) of wafer stage WST (wafer tableWTB) using X scale 39X₁ previously described. Further, head unit 62Dconstitutes a multiple-lens (seven-lens, in this case) X linear encoder70D (refer to FIG. 7) that measures the X-position of wafer stage WST(wafer table WTB) using X scale 39X₂ previously described.

Here, distance WD between adjacent X heads 66 (to be more accurate, theirradiation point of the measurement beam generated by X head 66 on thescale) in the Y-axis direction that are equipped in each of head units62B and 62D is set shorter than half the width of X scales 39X₁ and 39X₂(to be more accurate, the length of grid line 37) in the Y-axisdirection. Accordingly, of the X heads 66 which head units 62B and 62Dare equipped with, at least two heads face the corresponding X scales39X₁ and 39X₂ at the time of the exposure and the like, except for timessuch as switching (linkage) which will be described later. Morespecifically, of the measurement beams which each seven X heads 66generate, at least two measurement beams each can be irradiated on thecorresponding X scales 39X₁ and 39X₂. Incidentally, the distance betweenX head 66 ₈ farthest to the −Y side of head unit 62B and X head 66 ₇farthest to the +Y side of head unit 62D is set slightly narrower thanthe width of wafer table WTB in the Y-axis direction so that switching(linkage described below) becomes possible between the two X heads bythe movement of wafer stage WST in the Y-axis direction.

Incidentally, in the placement of X head 66 in the embodiment, on theswitching (linkage) described above, only X head 66 ₈ farthest to the −Yside among X heads 66 belonging to head unit 62B faces the correspondingX scale 39X₁, and only X head 66 ₇ farthest to the +Y side among X heads66 belonging to head unit 62D faces the corresponding X scale 39X₂. Morespecifically, only one each of the X heads 66 faces X scales 39X₁ and39X₂. Therefore, the distance between head unit 62B and 62D can benarrower than distance WD, and at least one of X heads 66 ₆ and 66 ₉ canbe made to face the corresponding X scales at the same time, as well asX head 66 ₈ and X head 66 ₇ which face the corresponding X scales alsoat the time of switching (linkage).

In the embodiment, furthermore, as shown in FIG. 4, head units 62E and62F are respectively arranged a predetermined distance away on the −Yside of head units 62C and 62A. These head units 62E and 62F are fixedto the mainframe (not shown) holding projection unit UP in a suspendedstate, via a support member.

Head unit 62E is equipped with seven Y heads 67 ₁ to 67 ₇, as shown inFIG. 5. More particularly, head unit 62E is equipped with five Y heads67 ₁ to 67 ₅ placed on the −X side of the secondary alignment system AL2₁ on reference axis LA at substantially the same distance as distance WDpreviously described, and two Y heads 67 ₆ and 67 ₇ placed on the +Yside of the secondary alignment system AL2 ₁ a predetermined distanceaway in the +Y direction from reference axis LA, at distance WD parallelto reference axis LA. Incidentally, the distance between Y heads 67 ₅and 67 ₆ in the X-axis direction is also set to WD. Hereinafter, Y heads67 ₁ to 67 ₇ will also be described, appropriately, as Y head 67.

Head unit 62F is symmetrical to head unit 62E with respect to referenceaxis LV previously described, and is equipped with seven Y heads 68 ₁ to68 ₇ which are placed in symmetry to the seven Y heads 67 with respectto reference axis LV. Hereinafter, Y heads 68 ₁ to 68 ₇ will also bedescribed, appropriately, as Y head 68.

On alignment operation and the like, at least two each of Y heads 67 and68 face Y scales 39Y₂ and 39Y₁, respectively. More specifically, of themeasurement beams which each seven Y heads 67 and 68 generate, at leasttwo measurement beams each can be constantly irradiated on Y scales 39Y₁and 39X₂ at the time of alignment and the like. The Y position (and θzrotation) of wafer stage WST is measured by these Y heads 67 and 68(more specifically, Y encoders 70E and 70F configured by Y heads 67 and68).

Further, in the embodiment, at the time of baseline measurement and thelike of the secondary alignment system, Y head 67 ₅ and 68 ₃ which areadjacent to the secondary alignment systems AL2 ₁ and AL2 ₄ in theX-axis direction face the pair of reference gratings 52 of FD bar 46,respectively, and by Y heads 67 ₅ and 68 ₃ that face the pair ofreference gratings 52, the Y position of FD bar 46 is measured at theposition of each reference grating 52. In the description below, theencoders configured by Y heads 67 ₅ and 68 ₃ which face a pair ofreference gratings 52, respectively, are referred to as Y linearencoders (also shortly referred to as a “Y encoder” or an “encoder” asneeded) 70E₂ and 70F₂. Further, for identification, Y encoders 70E and70F configured by Y heads 67 and 68 that face Y scales 39Y₂ and 39Y₁described above, respectively, will be referred to as Y encoders 70E₁and 70F₁.

The measurement values of linear encoders 70A to 70F described above issupplied to main controller 20, and main controller 20 controls theposition within the XY plane of wafer stage WST based on threemeasurement values of linear encoders 70A to 70D or on three measurementvalues of encoders 70B, 70D, 70E₁, and 70F₁, and also controls therotation in the θz direction of FD bar 46 based on the measurementvalues of linear encoders 70E₂ and 70F₂.

In exposure apparatus 100 of the embodiment, as shown in FIGS. 4 and 6,a multipoint focal position detecting system (hereinafter, shortlyreferred to as a “multipoint AF system”) by an oblique incident methodis arranged, which is composed of an irradiation system 90 a and aphotodetection system 90 b, having a configuration similar to the onedisclosed in, for example, U.S. Pat. No. 5,448,332 and the like. In theembodiment, as an example, irradiation system 90 a is placed on the +Yside of the −X end portion of head unit 62E previously described, andphotodetection system 90 b is placed on the +Y side of the +X endportion of head unit 62F previously described in a state of opposingirradiation system 90 a. The multipoint AF system (90 a, 90 b) is fixedto the lower surface of the mainframe (not shown) holding projectionunit PU previously described.

A plurality of detection points of the multipoint AF system (90 a, 90 b)are placed at a predetermined distance along the X-axis direction on thesurface to be detected. In the embodiment, the plurality of detectionpoints are placed, for example, in the arrangement of a matrix havingone row and M columns (M is a total number of detection points) orhaving two rows and N columns (N=M/2). In FIGS. 4 and 6, the pluralityof detection points to which a detection beam is severally irradiatedare not individually shown, but are shown as an elongate detection area(beam area) AF that extends in the X-axis direction between irradiationsystem 90 a and photodetection system 90 b. Because the length ofdetection area AF in the X-axis direction is set to around the same asthe diameter of wafer W, by only scanning wafer W in the Y-axisdirection once, position information (surface position information) inthe Z-axis direction across the entire surface of wafer W can bemeasured.

As shown in FIG. 6, in the vicinity of both end portions of beam area AFof the multipoint AF system (90 a, 90 b), heads 72 a and 72 b, and 72 cand 72 d of surface position sensors for Z position measurement(hereinafter, shortly referred to as “Z heads”) are arranged each in apair, in symmetrical placement with respect to reference axis LV. Zheads 72 a to 72 d are fixed to the lower surface of a main frame (notshown).

As Z heads 72 a to 72 d, for example, a head of an optical displacementsensor similar to an optical pickup used in a CD drive device is used. Zheads 72 a to 72 d irradiate measurement beams to wafer table WTB fromabove, and by receiving the reflected lights, measure the positionalinformation (surface position information) of the surface of wafer tableWTB in the Z-axis direction orthogonal to the XY plane at theirradiation point. Incidentally, in the embodiment, a configuration isemployed where the measurement beams of the Z heads are reflected by thereflection grating configuring the Y scales 39Y₁ and 39Y₂ previouslydescribed.

Furthermore, as shown in FIG. 6, head units 62A and 62C previouslydescribed are respectively equipped with Z heads 76 _(j) and 74 _(i) (i,j=1-9), which are nine heads each, at the same X position as Y heads 65_(j) and 64 _(i) (i, j=1-9) that head units 62A and 62C are respectivelyequipped with, with the Y position shifted. In this case, Z heads 76 ₅to 76 ₉ and 74 ₁ to 74 ₅, which are five heads each on the outer sidebelonging to head units 62A and 62C, respectively, are placed parallelto reference axis LH a predetermined distance away in the +Y directionfrom reference axis LH. Further, Z heads 76 ₁ and 76 ₂ and Z heads 74 ₈and 74 ₉, which are two heads on the innermost side belonging to headunits 62A and 62 c, respectively, are placed on the +Y side ofprojection unit PU, and the remaining Z heads 76 ₃ and 76 ₄, and 74 ₆,and 74 ₇ are placed on the −Y side of Y heads 65 ₃ and 65 ₄, and 64 ₆and 64 ₇, respectively. And Z heads 76 _(j) and 74 _(i), which are nineheads each belonging to head units 62A and 62C, respectively, are placedsymmetric to each other with respect to reference axis LV. Incidentally,as each of the Z heads 76 _(j) and 74 _(i), an optical displacementsensor head similar to Z heads 72 a to 72 d described above is used.

The distance of the nine Z heads 76 _(j) and 74 _(i) (to be moreaccurate, the irradiation point of the measurement beam generated by theZ heads on the scale) in the X-axis direction that are equipped in eachof head units 62A and 62C is set equal to distance WD of Y heads 65 and64 in the X-axis direction. Accordingly, similar to Y heads 65 and 64,of each nine Z heads 76 _(j) and 74 _(i), at least two heads eachconstantly face the corresponding Y scales 39Y₁ and 39Y₂ at the time ofthe exposure and the like. More specifically, of the measurement beamswhich each nine Z heads 76 _(j) and 74 _(i) generate, at least twomeasurement beams each can be irradiated on the corresponding Y scales39Y₁ and 39Y₂.

Z heads 72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉ connect to maincontroller 20 via a signal processing/selection device 170 as shown inFIG. 7, and main controller 20 selects an arbitrary Z head from Z heads72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉ via signalprocessing/selection device 170 and makes the head move into anoperating state, and then receives the surface position informationdetected by the Z head which is in an operating state via signalprocessing/selection device 170. In the embodiment, a surface positionmeasurement system 180 (a part of measurement system 200) that measurespositional information of wafer stage WST in the Z-axis direction andthe direction of inclination with respect to the XY plane is configured,including Z heads 72 a to 72 d, 74 ₁ to 74 ₉, and 76 ₁ to 76 ₉, andsignal processing/selection device 170.

Furthermore, in exposure apparatus 100, above reticle stage RST, a pairof reticle alignment detection systems 13A and 13B (not shown in FIG. 1,refer to FIG. 7) consisting of TTR (Through The Reticle) alignmentsystems which use lights of the exposure wavelength is arranged.Detection signals of reticle alignment detection systems 13A and 13B aresupplied to main controller 20 via an alignment signal processing system(not shown).

FIG. 7 shows the main configuration of the control system of exposureapparatus 100. The control system is mainly configured of maincontroller 20 composed of a microcomputer (or workstation) that performsoverall control of the entire apparatus. Incidentally, in FIG. 7,various sensors such as uneven illuminance measuring sensor 94, aerialimage measuring instrument 96 and wavefront aberration measuringinstrument 98 that are arranged at measurement stage MST arecollectively shown as a sensor group 99.

In exposure apparatus 100 of the embodiment, because the placement ofthe X scales and the Y scales on wafer table WTB previously describedand the placement of the X heads and the Y heads previously describedwere employed, as shown in FIGS. 8A and 8B, in the effective strokerange (a range where the stage moves for alignment and exposureoperation in the embodiment) of wafer stage WST, Y scales 39Y₁ and 39Y₂face Y heads 65 and 64 (head units 62A and 62C) or Y heads 68 and 67(head units 62F and 62E), while X head 66 (head unit 62B or 62D) alsofaces one of X scales 39X₁ and 39X₂ without fail. Incidentally, in FIGS.8A and 8B, the heads which face the corresponding X scales and Y scalesare shown circled by a solid line.

As previously described, at least two heads of each of the head units62A to 62F constantly face the corresponding scale except for a part ofthe units (to be more precise, at least two measurement beams can beirradiated on the corresponding scale except for a part of the units).Therefore, main controller 20 pairs at least two heads facing the scaleand uses the pairs for each of the head units 62A to 62F. Then, maincontroller 20 constantly monitors the measurement values of the twoheads, and uses one of the measurement values as a representative of thepair of heads (or the head unit to which the two heads belong). Of thetwo heads, main controller 20, for example, uses the head which facesthe scale first as a priority head, and the head which faces the scalelater on as an auxiliary head. Or, main controller 20 can use the headnear the center of the scale in a direction (the X-axis direction in thecase of a Y scale) orthogonal to the longitudinal direction as apriority head, and the remaining head can be used as an auxiliary head.Main controller 20 can normally use the measurement values of thepriority head as a representative, and in the case abnormality occurs inthe output (measurement value) of the priority head, the measurementvalues of the auxiliary head can be used as the measurement values ofthe pair of heads (or head unit). Main controller 20 monitors themeasurement values of the six head units according to this handling.

Main controller 20 monitors photoelectric conversion signals output by alight receiving element inside the head to inspect the correctness ofthe measurement result of the priority head, especially to inspect theoutput abnormality of the priority head due to malfunction (abnormality)of the head, and when there are no photoelectric conversion signals(when the signal intensity is zero) or when the signal intensity is atan extremely low level, main controller 20 judges that abnormality hasoccurred, and otherwise decides it is normal.

Therefore, in the effective stroke range of wafer stage WST previouslydescribed, by controlling each motor that configures stage drive system124 based on three measurement values out of encoders 70A to 70D, or onthree measurement values out of 70B, 70D, 70E₁, and 70F₁, positionalinformation (including the rotation information in the θz direction) ofwafer stage WST within the XY plane can be controlled with highprecision.

Further, when main controller 20 drives wafer stage WST in the X-axisdirection as shown by an outlined arrow in FIG. 8A, the pair of Y heads65 and 64, which measures the position of wafer stage WST in the Y-axisdirection, is sequentially switched to an adjacent pair of heads asshown by an arrow e1 in FIG. 8A. To enter the details, as for Y head 65,the pair of heads switched is from the pair 65 ₃ and 65 ₄ surrounded bythe circle in a solid line to the pair 65 ₄ and 65 ₅ surrounded by thecircle in a dotted line, and as for Y head 64, the pair of headsswitched is from the pair 64 ₃ and 64 ₄ surrounded by the circle in asolid line to the pair 64 ₄ and 64 ₅ surrounded by the circle in adotted line. In this case, one head (65 ₄, 64 ₄) is common in the pairof heads before the switching and the pair of heads after the switching.

In the embodiment, in order to perform the switching (linkage) of the Yheads 65 and 64 smoothly, as is previously described, of the Y heads 65and 64 that head units 62A and 62C are equipped with, the distance(twice the distance WD of adjacent heads) between the two heads to beswitched (for example, in the example in FIG. 8A, Y heads 65 ₃ and 65 ₅,and 64 ₃ and 64 ₅) is set smaller than the width of Y scales 39Y₁ and39Y₂ in the X-axis direction. In other words, distance WD of adjacent Yheads is set it is narrower than half the width of Y scales 39Y₁ and39Y₂ in the X-axis direction.

Further, in the case of Sec-BCHK (beginning of lot) described below,when main controller 20 drives wafer stage WST in the X-axis direction,main controller 20 sequentially switches the pair of heads in Y heads 67and 68 measuring the position of wafer stage WST in the Y-axis directionto the adjacent heads similar to the description above.

Further, in the embodiment, as previously described, because distance WDof adjacent X heads 66 that head units 62B and 62D are equipped with isnarrower than half the width of X scales 39X₁ and 39X₂ in the Y-axisdirection, when main controller 20 drives wafer stage WST in the Y-axisdirection as shown by an outlined arrow in FIG. 8B, the pair of X heads66, which measures the position of wafer stage WST in the X-axisdirection, is sequentially switched to an adjacent pair of heads asshown by an arrow e2 in FIG. 8B, similar to the description above. Toenter the details, the pair of heads is switched from the pair 66 ₉ and66 ₁₀ surrounded by the circle in a solid line to the pair 66 ₈ and 66 ₉surrounded by the circle in a dotted line. In this case, one head 66 ₉is common in the pair of heads before the switching and the pair ofheads after the switching.

In the embodiment, a method is employed where the encoder head used formeasuring the position of wafer stage WST is switched from a pair ofheads (for example, Eh1 and Eh2) to another pair of heads (Eh2 and Eh3)including one of the heads (Eh2), with the movement of wafer stage WST.However, as well as this method, a modified method of switching toanother pair of heads (Eh3 and Eh4) which does not include a common headfrom a certain pair of heads (for example, Eh1 and Eh2) can be adopted.Also in this deformation method, similar to the method described above,the measurement values of the priority head should be used normally, andat the time of abnormality, the measurement values of the auxiliary headshould be used representatively as the measurement values of the pair ofheads (or the head unit to which these heads belong).

Incidentally, as the cause of abnormality being generated in themeasurement values of the encoder, there is two major causes, that is, acause coming from malfunction of the encoder head (head), and a causecoming from abnormality in the scale on which the measurement beam isirradiated. As an example of the former case, a mechanical failure ofthe head can be representatively given. To be concrete, a failure in thehead itself, a failure in the measurement beam light source, a situationwhere water droplets adhere on the head and the like can be given. Asituation where the intensity of the measurement beam becomes extremelylow, if not the measurement beam light source fails to operate, can besaid to be a cause coming from the head. Meanwhile, as an example of thelatter case, the case can be given in which the liquid of the liquidimmersion area remains or foreign materials such as dust and the likeadheres on the scale surface, and the measurement beam scans theremaining liquid or the adhered foreign material.

The method in the embodiment in which a pair of heads configured by apriority head and an auxiliary head is made to constantly face at leastone corresponding scale is effective to abnormality of the measurementvalues due to malfunction of the heads, and is also effective toabnormality of the measurement values due to abnormality in the scales.

Incidentally, because the optical path length of the two beams which aremade to interfere is extremely short and substantially equal in encoders70A to 70F used in the embodiment, the influence of air fluctuation canbe almost ignored. The resolution of each encoder, for example, isaround 0.1 nm.

Next, a baseline measurement (hereinafter, also appropriately referredto as Sec-BCHK (beginning of lot)) of the secondary alignment system AL2_(n) (n=1-4) will be described, which is mainly performed just before(beginning of lot) starting the processing to the wafer of the lot. Inthis case, the base line of the secondary alignment system AL2 _(n)means the relative position of each (detection center of) secondaryalignment system AL2 _(n) with (the detection center of) primaryalignment system AL1 serving as a reference. Incidentally, the secondaryalignment system AL2 _(n) (n=1-4) has the position in the X-axisdirection set, for example, according to a shot map data of the waferwithin the lot.

a. On Sec-BCHK (beginning of lot), first of all, main controller 20detects a specific alignment mark on wafer W (a process wafer) at thebeginning of the lot using primary alignment system AL1 as shown in FIG.9A (refer to the star mark in FIG. 9A), makes a link between thedetection results and the measurement values of encoders 70A, 70E₁, and70F₁ at the time of the detection, and then stores them in memory. Inthe state shown in FIG. 9A, main controller 20 controls the position ofwafer stage WST within the XY plane, based on two pairs of Y heads 68 ₃and 68 ₄, and 67 ₄ and 67 ₅ (encoders 70E₁ and 70F₁) surrounded by ablack line circle facing Y scales 39Y₁ and 39Y₂, respectively, and apair of X heads 66 ₃ and 66 ₄ (encoder 70D) surrounded by a black linecircle facing X scale 39X₂.

b. Next, main controller 20 moves wafer stage WST in the −X direction bya predetermined distance, and detects (refer to the star mark in FIG.9B) the specific alignment mark described above using the secondaryalignment system AL2 ₁ as shown in FIG. 9B, makes a link between thedetection results and the measurement values of encoders 70E₁, 70F₁, and70D at the time of detection, and then stores them in memory. In thestate shown in FIG. 9B, main controller 20 controls the position ofwafer stage WST within the XY plane, based on two pairs of Y heads 68 ₁and 68 ₂, and 67 ₁ and 67 ₂ (encoders 70E₁ and 70F₁) surrounded by ablack line circle facing Y scales 39Y₁ and 39Y₂, respectively, and apair of X heads 66 ₃ and 66 ₄ (encoder 70D) surrounded by a black linecircle facing X scale 39X₂.

c. Similarly, main controller 20 sequentially moves wafer stage WST inthe +X direction, and sequentially detects the specific alignment markdescribed above using the remaining secondary alignment systems AL2 ₂,AL2 ₃, and AL2 ₄, makes a link between the detection results and themeasurement values of encoders 70E₁, 70F₁, and 70D at the time ofdetection, and then stores them in memory.

d. Then, based on the processing results of paragraph a. above and theprocessing results of paragraph b. or c. above, main controller 20respectively computes the base line of each secondary alignment systemAL2 _(n).

As described, by detecting the same alignment mark with primaryalignment system AL1 and each secondary alignment system AL2 _(n) usingwafer W (the process wafer) in the beginning of the lot, the baseline ofeach secondary alignment system AL2 _(n) is obtained, and by thisprocessing, a difference of the detection offset between the alignmentsystems due to the process is also consequently corrected.

In the embodiment, because head units 62E and 62F are each equipped withseven Y heads 67 and 68 whose positions are different in the X-axisdirection, when measuring the baseline of each secondary alignmentsystem AL2 _(n) described above, in the case of detecting the specificalignment mark on the wafer using any one of the secondary alignmentsystems AL2 _(n), as well as primary alignment system AL1, the Yposition of wafer stage WST at the time of the detection and the θzrotation can be measured and controlled, based on the measurement valuesof the pair of Y heads 68 and 67 (encoders 70F₁ and 70E₁), facing Yscales 39Y₁ and 39Y₂. Further, at this point, the X position of waferstage WST can be measured ad controlled, based on the measurement valuesof the pair of X heads 66 (encoder 70D) facing X scale 39X₂.

Incidentally, instead of the alignment mark on the wafer, for example,fiducial mark FM of measurement plate 30 on wafer stage WST, orreference mark M of FD bar 46 on measurement stage MST can be used, toperform baseline measurement of the secondary alignment system AL2 _(n).

In exposure apparatus 100 of the embodiment, a parallel processingoperation using wafer stage WST and measurement stage MST is performed,basically in the same procedure as the exposure apparatus disclosed inthe embodiment of the pamphlet of International Publication 2007/097379previously described. Because this parallel processing operation issimilar to the exposure apparatus disclosed in the embodiment of thepamphlet of International Publication 2007/097379 previously describedexcept for the following two points, a detailed description will beomitted.

The first point is, when abnormality occurs in the output of one of thepriority heads (the X head or the Y head) used for position measurementof the encoder system which measures the positional information of waferstage WST in the case wafer stage WST is in the effective stroke areapreviously described, main controller 20 uses the measurement values ofthe auxiliary head which configures a pair of heads with the priorityhead as is previously described as the measurement values of the pair ofheads (or the head unit to which the two heads belong).

The second point is, for example, at the time of stepping operationbetween shots of wafer stage WST on the exposure operation by thestep-and-scan method, a switching of heads is performed by a switchingmethod in which the encoder head used for measuring, for example, the Xposition of wafer stage WST is switched from a pair of heads (forexample, Eh1 and Eh2) to another pair of heads (Eh2 and Eh3) whichinclude one of the heads (Eh2).

As described above, according to exposure apparatus 100 of theembodiment, because two or more corresponding Y heads constantly face Yscales 39Y₁ and 39Y₂ arranged on wafer stage WST when wafer stage WST isin the effective stroke area previously described, main controller 20can constantly measure the positional information of wafer stage WST inthe periodic direction (Y-axis direction) of the grating section of Yscales 39Y₁ and 39Y₂ and rotation information in the θz direction, usingat least one of the measurement results of the two Y heads. Further,when wafer stage WST is in the effective stroke area previouslydescribed, two or more corresponding X heads constantly face either oneof X scales 39X₁ and 39X₂ arranged on wafer stage WST, except for someexceptional cases (in the case wafer stage WST is located at a positionwhere X head 66 ₈ of head unit 62B and X head 66 ₇ of head unit 62D canbe switched). Accordingly, main controller 20 can constantly measure thepositional information of wafer state WST in the periodic direction(X-axis direction) of the grating section of Y scales 39Y₁ and 39Y₂, byusing least one of the measurement results of the two X heads.

Further, in the case abnormality (or abnormality due to the abnormalityof the scale) due to the abnormality of the head occurs in themeasurement information of the priority head of at least the two headslocated in the effective area (a grating section) on each scale, maincontroller 20 switches the measurement information used in positioncontrol of wafer stage WST from the measurement information obtained bythe priority head to the measurement information from the auxiliaryhead. By this switching, it becomes possible to securely measure thepositional information of wafer stage WST in the periodic direction ofthe grating section which each scale has.

Further, according to the exposure apparatus of the embodiment, encodersystem 150 included in measurement system 200 has seven Y heads 67 and68 whose positions are different in the X-axis direction and configure apart of head units 62E and 62F, respectively, placed on the outer sidesof both the detection area of primary alignment system AL1 and thedetection area of secondary alignment system AL2 ₁ to AL2 ₄. And, onalignment and the like, main controller 20 measures the positionalinformation of wafer stage WST in the Y-axis direction (and positionalinformation in the θz direction), based on measurement values of a pairof Y heads 68 and 67 (Y linear encoders 70F₁ and 70E₁) which face thepair of Y scales 39Y₁ and 39Y₂, respectively.

Therefore, for example, on Sec-BCHK (beginning of lot) previouslydescribed, also in the case when main controller 20 moves wafer stageWST in the X-axis direction in order to detect the specific alignmentmarks (or fiducial mark FM on wafer stage WST) on wafer W held by waferstage WST using each of primary alignment system AL1 and the secondaryalignment systems AL2 ₁ to AL2 ₄, in and the like, it becomes possibleto measure at least the position of wafer stage WST in the Y-axisdirection (and rotation in the θz direction) by Y linear encoders 70E₁and 70F₁ whose short-term stability of measurement is good. Accordingly,based on detection results of alignment systems AL1, and AL2 ₁ to AL2 ₄and the measurement values of Y linear encoder 70E₁ and 70F₁ at the timeof the detection, main controller 20 can obtain the positionalinformation of the mark (the specific alignment mark (or fiducial markFM on wafer stage WST) in the Y-axis direction with good precision.Further, the position of wafer stage WST in the X-axis direction in caseof Sec-BCHK (beginning of lot) is measured by the pair of X heads 66(encoder 70D) which faces X scale 39X₂. Accordingly, the base line (theX-axis direction and the Y-axis direction) of secondary alignmentsystems AL2 ₁ to AL2 ₄, can be obtained with high accuracy at thebeginning of every lot.

Further, in the embodiment, the baseline of the secondary alignmentsystems AL2 ₁ to AL2 ₄ (the X-axis direction and the Y-axis direction)is measured (at each wafer exchange) at predetermined intervals.

And, by repeating a movement operation between shots in which waferstage WST is moved to a scanning starting position (accelerationstarting position) for exposure of each shot area on wafer W and ascanning exposure operation in which a pattern formed on reticle R istransferred onto each shot area by a scanning exposure method, based onthe latest baseline obtained in such a manner and the results of waferalignment (EGA), it becomes possible to transfer the pattern of reticleR on the plurality of shot areas on wafer W with good precision (overlayaccuracy). Furthermore, in the embodiment, because a high-resolutionexposure can be realized by liquid immersion exposure, a fine patterncan be transferred with good precision on wafer W also from thisviewpoint.

Further, according to exposure apparatus 100 of the embodiment, of eachof the seven Y heads 67 and 68 which are equipped in head units 62E and62F, the two Y heads 67 ₆ and 67 ₇, and 68 ₁ and 68 ₂ located on theinnermost side have positions different from the other Y heads in theY-axis direction. This allows the two Y heads 67 ₆ and 67 ₇, and 68 ₁and 68 ₂ located on the innermost side to be placed in an empty space inthe periphery of alignment systems AL1, and AL2 ₁ to AL2 ₄, or morespecifically, to be placed in accordance with the placement of alignmentsystems AL1, and AL2 ₁ to AL2 ₄.

Further, because the distance of each of the seven Y heads 67 and 68which are equipped in head units 62E and 62F, respectively, in theX-axis direction is narrower than half the width (to be more precise,the length of grid line 38) of Y scales 39Y₁ and 39Y₂ in the X-axisdirection, when wafer stage WST moves in the X-axis direction, the pairof Y heads used for measuring the positional information of wafer stageWST in the Y-axis direction is switched to an adjacent pair of Y heads(however, one of the heads of the pair of Y heads is in common with thepreceding pair of heads) without any problems, and the measurementvalues are succeeded before and after the switching. Accordingly, onSec-BCHK and the like described above, at least two each of Y heads 67and 68 face Y scales 39Y₂ and 39Y₁, respectively, and by the pair of Yheads 67 and 68 (that is, Y encoders 70E₁ and 70F₁ configured by thepair of Y heads 67 and 68), the Y position (and θz rotation) of waferstage WST is measured.

Further, at the time of detection of the alignment mark on wafer W byalignment systems AL1, and AL2 ₁ to AL2 ₄, main controller 20 selectstwo each of Y heads 67 and 68 which respectively face Y scales 39Y₂ and39Y₁ from each of the seven Y heads 67 and 68 of head units 62E and 62F,as well as selects two X heads 66 which face the corresponding X scales39X₁ and 39X₂ from a plurality of X heads 66 of head units 62B and 62D,and based on the measurement values of the two pair of Y heads that havebeen selected and the measurement values of the pair of X heads thathave been selected, main controller 20 controls the position of waferstage WST in the XY plane and rotation (θz rotation).

Modified Example

Incidentally, in the embodiment above, two encoder heads (heads) wereconstantly made to face a common scale to measure positional informationof wafer stage WST in the XY movement plane in a stable manner and withhigh accuracy. And, of a pair of heads consisting of the two heads,measurement values of a priority head was used, and in the caseabnormality was generated in the measurement value of the priority headdue to malfunction of the head (or abnormality of the scale),measurement values of the other auxiliary head was to be used. However,as well as this, as a measurement method constantly using the two heads,which are the priority head and the auxiliary head, various modifiedexamples can be considered.

Some representative examples will be shown below, which are modifiedexamples, referring to FIGS. 10A to 12. Incidentally, in FIG. 10A toFIG. 12, scale SY (more specifically, the wafer stage) is to be moved inthe −X direction. Further, scale SY is to be indicated as a Y scale, andthe head is to be indicated as a Y head.

As a first modified example, two heads, which are a priority head and anauxiliary head, can be made into a set (to be referred to as a headset), and an example where at least one set is constantly made to facethe scale can be given. In this first modified example, as shown in FIG.10A, a head set Hs1 consisting of two heads Eh1 and Eh2 placed close tothe longitudinal direction (the Y-axis direction) of scale SY, andanother head set Hs2 consisting of two heads Eh3 and Eh4 placed close tothe Y-axis direction face one scale, SY. In this first modified example,a plurality of head sets is prepared, configured of two heads inproximity to the Y-axis direction, and these head sets are placed inparallel with the X-axis direction at a distance smaller than theeffective width of scale SY. Accordingly, one head set will constantlyface scale SY.

When scale SY (more specifically, the wafer stage) moves in the −Xdirection from the state shown in FIG. 10A, head set Hs1 moves off ofscale SY. To be more precise, irradiation points of measurement beamsoutgoing from the two heads Eh1 and Eh2 constituting head set Hs1, ormore specifically, measurement points of heads Eh1 and Eh2 move off froman effective area of scale SY. Therefore, before head set Hs1 moves offfrom scale SY, main controller 20 switches the head set controlling thestage position from head set Hs1 to head set Hs2.

This first modified example is effective to abnormality of themeasurement values due to malfunction of the heads previously described,and is also effective to abnormality of the measurement values due toabnormality in the scales.

A second modified example following the first modified example describedabove is shown in FIG. 10B. As it can be seen when comparing FIGS. 10Band 10A, in the first modified example, a configuration was employedwhere the two heads configuring the head set each scanned a differentmeasurement point, whereas in the second modified example, aconfiguration is employed where the two heads configuring the head setscan the same measurement point. Accordingly, in the first modifiedexample, the two heads show different measurement values, whereas in thesecond modified example, the two heads normally show measurement valuesequal to each other. By employing the configuration in the secondmodified example, even if abnormality occurs in the measurement valuesof a priority head due to mechanical failure and the like in thepriority head, which is one of the two heads configuring the head set,the normal measurement values of the other head, or the auxiliary head,can be used as the measurement values of the head set. Accordingly,abnormality is not detected in the measurement results as the head set.

Incidentally, the difference in the second modified example and thefirst modified example is only whether the position of the measurementpoint of the two heads configuring the head set is the same or not.Accordingly, the placement of each head set and the individual headsconfiguring each head set in the second modified example should be setin a similar manner as the first modified example. By this arrangement,the procedure of the switching process also becomes the same.

In the first and second modified examples described above, the two headsconfiguring the head set is placed in parallel in the periodic direction(the Y-axis direction) of the scale. In correspondence with theseexamples, an example can also be considered where the placement is inparallel in a direction (the X-axis direction) orthogonal to theperiodic direction of the scale.

FIG. 11A shows a third modified example, in correspondence with thefirst modified example in FIG. 10A. In the third modified example,similar to the first modified example, two heads, which are a priorityhead and a auxiliary head, are made into a set, and at least one set isconstantly made to face the scale. However, in FIG. 11A, it is differentfrom the first modified example, and a head set Hs1 consisting of twoheads Eh1 and Eh2 placed close to the effective width direction (theX-axis direction) of scale SY, and another head set Hs2 consisting oftwo heads Eh3 and Eh4 placed close to the X-axis direction face onescale, SY. In this third modified example, a plurality of head sets isprepared, configured of two heads in proximity to the X-axis direction,and these head sets are placed in parallel with the X-axis direction sothat one head set constantly faces scale SY. However, the distance oftwo adjacent head sets, is set to a distance so that the irradiationpoints (measurement points) of the measurement beams outgoing from (allfour heads configuring) the two head sets are located within theeffective area of scale SY, as shown in FIG. 11A.

When scale SY (more specifically, the wafer stage) moves in the −Xdirection from a state shown in FIG. 11A, the measurement point of headEh1 moves off from the effective area of scale SY. If, supposing thathead Eh1 was chosen as the priority head of head set Hs1, the maincontroller 20 switches the priority head to head Eh2 at a point in timewhen head EH1 moves off from scale SY. Furthermore, when scale SY movesin the −X direction, then the measurement point of head Eh2 moves offfrom scale SY. Therefore, by this point in time at the latest, or morespecifically, before the measurement point of both heads Eh1 and Eh2configuring head set Hs1 moves off from scale SY, the head setcontrolling the stage position is switched from head set Hs1 to head setHs2.

This third modified example, similar to the first modified example, iseffective not only to abnormality of the measurement values due tomalfunction of the heads previously described, but is also effective toabnormality of the measurement values due to abnormality in the scales.

A fourth modified example following the third modified example describedabove is shown in FIG. 11B. As it can be seen when comparing FIGS. 11Band 11A, in the third modified example, a configuration was employedwhere the two heads configuring the head set each scanned a differentmeasurement point, whereas in the fourth modified example, aconfiguration is employed where the same measurement point is scanned.Accordingly, in the third modified example, the two heads show differentmeasurement values, whereas in the fourth modified example, the twoheads normally show measurement values equal to each other. By theconfiguration in the fourth modified example, even if abnormality occursin the measurement values of a priority head of the two headsconfiguring the head set due to mechanical failure and the like in thepriority head, the normal measurement values of the other head, or theauxiliary head, can be used, therefore, abnormality is not detected inthe measurement results as the head set.

Incidentally, the difference in the fourth modified example and thethird modified example is only whether the position of the measurementpoint of the two heads configuring the head set is the same or not.Accordingly, the placement of each head set and the individual headsconfiguring each head set in the fourth modified example should be setin a similar manner as the third modified example. By this arrangement,the procedure of the switching process also becomes the same.

Further, as is obvious when comparing FIGS. 11B and 10B, since thefourth modified example and the second modified example are differentmerely regarding the proximity direction of the two heads whichconfigure the head set, the effect that can be obtained is the same.

Further, in the third modified example in FIG. 11A, the distance of twoadjacent head sets, was set to a distance so that the irradiation points(measurement points) of the measurement beams outgoing from (all fourheads configuring) the two head sets were located within the effectivearea of scale SY. However, by reason of the switching process of theheadset, the placement distance of the two adjacent headsets can be setto a placement distance in which the two heads (Eh3, Eh4) configuringone head set (Hs2) and one of the heads (Eh2) of the two heads (Eh1,Eh2) configuring the other head set (Hs1), or three heads (Eh2, Eh3, andEh4), face scale SY, as shown in FIG. 12.

Incidentally, in the four modified examples, while a head set consistingof one priority head and one auxiliary head was used, the number ofauxiliary heads is not limited to one, and a plurality of auxiliaryheads can be arranged. In the case of employing such a configuration,reliability of the measurement results improves because more measurementdata can be detected. Further, in the case the plurality of heads withinthe head set are observed to be at the same position in the transversedirection (the X-axis direction in the modified examples) of the scaleas in the four modified examples, priority cannot be given according tothe guidelines such as, “priority given to the head which becomeseffective first,” or “priority given to the head closer to the scalecenter.” Accordingly, it is desirable to decide a fixed priority orderin the headset in advance.

Incidentally, the configuration of each measurement device such as theencoder system described in the embodiment above is only an example, andit is a matter of course that the present invention is not limited tothis. Further, in the embodiment above, an example has been describedwhere the encoder system is employed that has a configuration where agrid section (a Y scale and an X scale) is arranged on a wafer table (awafer stage), and X heads and Y heads facing the grid section are placedexternal to the wafer stage, however, the present invention is notlimited to this, and as is disclosed in, for example, U.S. PatentApplication Publication No. 2006/0227309, an encoder system which isconfigured having an encoder head arranged on the wafer stage and has atwo-dimensional grid (or a linear grid section having a two-dimensionalplacement) facing the encoder heads placed external to the wafer stagecan also be adopted. In this case, at least two encoder heads can bearranged on a plurality of places on the wafer stage, for example, onthe four corners, and with one of the at least two encoder heads servingas a priority head and the remaining at least one encoder head servingas an auxiliary head, position control of the wafer stage can beperformed similarly as in the embodiment and the modified examplesabove. Incidentally, the at least two encoder heads can be placed inproximity on the wafer stage, or can be placed a predetermined distanceapart. Especially in the latter case, the heads can be placed along aradiation direction from the center of the wafer stage. Further, becausethe grating surface of the two-dimensional grid and the like arrangedexternal to the wafer stage faces downward, it is considered that theliquid of the liquid immersion area will not remain and foreignmaterials such as dust and the like will not adhere on the surface.Accordingly, because abnormality of the encoder head output due to theabnormality of the scale does not have to be considered, the controllerwhich performs the switching of the heads can decide to monitor only theoutput abnormality of the priority head due to the malfunction of thehead.

Further, in the embodiment and the modified examples above, while thecase has been described where the encoder head and the Z head wereseparately arranged, every encoder head can have a Z head, or eachencoder head can be equipped with a Z head, or each encoder head can bea head (sensor) that can perform position detection in two directions,which are the X-axis or Y-axis direction, and the Z-axis direction.Especially in the former case, the encoder head and the Z head can beintegrally arranged.

Further, in the embodiment and the modified examples above, malfunction(abnormality) of the encoder head includes gradient of the head or lossof telecentricity, besides mechanical failure. Further, in the case ofthe type of encoder system which has a head arranged on the stage and ascale arranged above the head, the case when foreign materials(including, for example, the liquid for liquid immersion) adhere on thehead is included in the abnormality (malfunction) of the encoder head.Further, not only in the case when the position becomes unmeasurable,but the case when the measurement accuracy exceeds a permissible value(the output (intensity) of the encoder head results to be outside thepermissible range) is also included in the abnormality of the encoderhead.

Further, in the embodiment above, while the case has been describedwhere head units 62E and 62F each are equipped with seven Y heads, thenumber is not an issue as long as there are Y heads arranged on bothsides of a plurality of mark detection systems (in the embodiment above,alignment systems AL1, and AL2 ₁ to AL2 ₄). The important thing is thatin each of the plurality of mark detection systems, at least two or moreeach of Y heads 68 and 67 are to face a pair of Y scales 39Y₁ and 39Y₂when detecting the specific alignment mark on wafer W. Further, in theembodiment above, while the case has been described where the Y positionof the two Y heads which were located innermost among the plurality of Yheads arranged on both of the outer sides of the plurality of markdetection systems were different from the other Y heads, the Y positionof any other Y heads can also be different. The important thing is, theY position of an arbitrary Y head should be different from the Yposition of other Y heads, in correspondence with the empty space. Or,in the case there is enough empty space on both of the outer sides ofthe plurality of mark detection systems, all the Y heads can be placedat the same Y position.

Further, the number of mark detection systems (alignment systems) is notlimited to five, and while it is desirable that two or more markdetection systems whose position of the detection area is different in asecond direction (the X-axis direction in the embodiment above), thenumber is not an issue in particular.

Incidentally, in the embodiment above, while the lower surface of nozzleunit 32 and the lower end surface of the tip optical element ofprojection optical system PL were substantially flush, as well as this,for example, the lower surface of nozzle unit 32 can be placed nearer tothe image plane (more specifically, to the wafer) of projection opticalsystem PL than the outgoing surface of the tip optical element. That is,the configuration of local liquid immersion device 8 is not limited tothe configuration described above, and the configurations which aredescribed in, for example, EP Patent Application Publication No.1420298, U.S. Patent Application Publication 2006/0231206, U.S. PatentApplication Publication 2005/0280791, and U.S. Pat. No. 6,952,253 andthe like can also be used. Further, as disclosed in, for example, U.S.Patent Application Publication No. 2005/0248856, the optical path on theobject plane side of the tip optical element can also be filled withliquid, in addition to the optical path on the image plane side of thetip optical element. Furthermore, a thin film that is lyophilic and/orhas dissolution preventing function may also be formed on the partialsurface (including at least a contact surface with liquid) or the entiresurface of the tip optical element. Incidentally, quartz has a highaffinity for liquid, and also needs no dissolution preventing film,while in the case of fluorite, at least a dissolution preventing film ispreferably formed.

Incidentally, in the embodiment above, pure water (water) was used asthe liquid, however, it is a matter of course that the present inventionis not limited to this. As the liquid, a chemically stable liquid thathas high transmittance to illumination light IL and is safe to use, suchas a fluorine-containing inert liquid can be used. As thefluorine-containing inert liquid, for example, Fluorinert (the brandname of 3M United States) can be used. The fluorine-containing inertliquid is also excellent from the point of cooling effect. Further, asthe liquid, liquid which has a refractive index higher than pure water(a refractive index is around 1.44), for example, liquid having arefractive index equal to or higher than 1.5 can be used. As this typeof liquid, for example, a predetermined liquid having C—H binding or O—Hbinding such as isopropanol having a refractive index of about 1.50,glycerol (glycerin) having a refractive index of about 1.61, apredetermined liquid (organic solvent) such as hexane, heptane ordecane, or decalin (decahydronaphthalene) having a refractive index ofabout 1.60, or the like can be cited. Alternatively, a liquid obtainedby mixing arbitrary two or more of these liquids may be used, or aliquid obtained by adding (mixing) at least one of these liquids to(with) pure water may be used. Alternatively, as the liquid, a liquidobtained by adding (mixing) base or acid such as H⁺, Cs⁺, K⁺, Cl⁻, SO₄²⁻, or PO₄ ²⁻ to (with) pure water can be used. Moreover, a liquidobtained by adding (mixing) particles of Al oxide or the like to (with)pure water can be used. These liquids can transmit ArF excimer laserlight. Further, as the liquid, liquid, which has a small absorptioncoefficient of light, is less temperature-dependent, and is stable to aprojection optical system (tip optical member) and/or a photosensitiveagent (or a protection film (top coat film), an antireflection film, orthe like) coated on the surface of a wafer, is preferable. Further, inthe case an F2 laser is used as the light source, fomblin oil can beselected. Further, as the liquid, a liquid having a higher refractiveindex to illumination light IL than that of pure water, for example, arefractive index of around 1.6 to 1.8 may be used. As the liquid,supercritical fluid can also be used. Further, the tip optical elementof projection optical system PL may be formed by quartz (silica), orsingle-crystal materials of fluoride compound such as calcium fluoride(fluorite), barium fluoride, strontium fluoride, lithium fluoride, andsodium fluoride, or may be formed by materials having a higherrefractive index than that of quartz or fluorite (for example, equal toor higher than 1.6). As the materials having a refractive index equal toor higher than 1.6, for example, sapphire, germanium dioxide, or thelike disclosed in the pamphlet of International Publication No.2005/059617, or kalium chloride (having a refractive index of about1.75) or the like disclosed in the pamphlet of International PublicationNo. 2005/059618 can be used.

Further, in the embodiment above, the recovered liquid may be reused,and in this case, a filter that removes impurities from the recoveredliquid is preferably arranged in a liquid recovery unit, a recovery pipeor the like.

Further, in the embodiment above, the case has been described where theexposure apparatus is a liquid immersion type exposure apparatus.However, the present invention is not limited to this, but can also beemployed in a dry type exposure apparatus that performs exposure ofwafer W without liquid (water).

Further, in the embodiment above, the case has been described where thepresent invention is applied to a scanning exposure apparatus by astep-and-scan method or the like. However, the present invention is notlimited to this, but may also be applied to a static exposure apparatussuch as a stepper. Even in the case of a stepper, because the positionof the stage on which the object subject to exposure is mounted can bemeasured using an encoder as in the embodiment described above, asimilar effect can be obtained. Further, the present invention can alsobe applied to a reduction projection exposure apparatus by astep-and-stitch method that synthesizes a shot area and a shot area, anexposure apparatus by a proximity methods a mirror projection aligner,or the like. Moreover, the present invention can also be applied to amultistage type exposure apparatus equipped with a plurality of waferstages, as is disclosed in, for example, the U.S. Pat. No. 6,590,634,the U.S. Pat. No. 5,969,441, the U.S. Pat. No. 6,208,407 and the like.

Further, the magnification of the projection optical system in theexposure apparatus of the embodiment above is not only a reductionsystem, but also may be either an equal magnifying system or amagnifying system, and projection optical system PL is not only adioptric system, but also may be either a catoptric system or acatodioptric system, and in addition, the projected image may be eitheran inverted image or an upright image. Further, the illumination areaand exposure area described above are to have a rectangular shape.However, the shape is not limited to rectangular, and can also becircular arc, trapezoidal, parallelogram or the like.

Incidentally, a light source of the exposure apparatus in the embodimentabove is not limited to the ArF excimer laser, but a pulse laser lightsource such as a KrF excimer laser (output wavelength: 248 nm), an F₂laser (output wavelength: 157 nm), an Ar₂ laser (output wavelength: 126nm) or a Kr2 laser (output wavelength: 146 nm), or an extra-highpressure mercury lamp that generates an emission line such as a g-line(wavelength: 436 nm), an i-line (wavelength: 365 nm) and the like canalso be used. Further, a harmonic wave generating unit of a YAG laser orthe like can also be used. Besides the sources above, as is disclosedin, for example, U.S. Pat. No. 7,023,610, a harmonic wave, which isobtained by amplifying a single-wavelength laser beam in the infrared orvisible range emitted by a DFB semiconductor laser or fiber laser asvacuum ultraviolet light, with a fiber amplifier doped with, forexample, erbium (or both erbium and ytterbium), and by converting thewavelength into ultraviolet light using a nonlinear optical crystal, canalso be used.

Further, in the embodiment above, illumination light IL of the exposureapparatus is not limited to the light having a wavelength equal to ormore than 100 nm, and it is needless to say that the light having awavelength less than 100 nm can be used. For example, in recent years,in order to expose a pattern equal to or less than 70 nm, an EUVexposure apparatus that makes an SOR or a plasma laser as a light sourcegenerate an EUV (Extreme Ultraviolet) light in a soft X-ray range (e.g.a wavelength range from 5 to 15 nm), and uses a total reflectionreduction optical system designed under the exposure wavelength (forexample, 13.5 nm) and the reflective mask has been developed. In the EUVexposure apparatus, the arrangement in which scanning exposure isperformed by synchronously scanning a mask and a wafer using a circulararc illumination can be considered, and therefore, the present inventioncan also be suitably applied to such an exposure apparatus. Besides suchan apparatus, the present invention can also be applied to an exposureapparatus that uses charged particle beans such as an electron beam oran ion beam.

Further, in the embodiment above, a transmissive type mask (reticle) isused, which is a transmissive substrate on which a predetermined lightshielding pattern (or a phase pattern or a light attenuation pattern) isformed. Instead of this reticle, however, as is disclosed in, forexample, U.S. Pat. No. 6,778,257, an electron mask (which is also calleda variable shaped mask, an active mask or an image generator, andincludes, for example, a DMD (Digital Micromirror Device) that is a typeof a non-emission type image display device (spatial light modulator) orthe like) on which a light-transmitting pattern, a reflection pattern,or an emission pattern is formed according to electronic data of thepattern that is to be exposed can also be used.

Further, for example, the present invention can also be applied to anexposure apparatus (lithography system) that forms line-and-spacepatterns on a wafer by forming interference fringes on the wafer.

Moreover, as disclosed in, for example, U.S. Pat. No. 6,611,316, thepresent invention can also be applied to an exposure apparatus thatsynthesizes two reticle patterns via a projection optical system andalmost simultaneously performs double exposure of one shot area by onescanning exposure.

Further, an apparatus that forms a pattern on an object is not limitedto the exposure apparatus (lithography system) described above, and forexample, the present invention can also be applied to an apparatus thatforms a pattern on an object by an ink-jet method.

Incidentally, an object on which a pattern is to be formed (an objectsubject to exposure to which an energy beam is irradiated) in theembodiment above is not limited to a wafer, but may be other objectssuch as a glass plate, a ceramic substrate, a film member, or a maskblank.

The use of the exposure apparatus is not limited only to the exposureapparatus for manufacturing semiconductor devices, but the presentinvention can also be widely applied, for example, to an exposureapparatus for transferring a liquid crystal display device pattern ontoa rectangular glass plate, and an exposure apparatus for producingorganic ELs, thin-film magnetic heads, imaging devices (such as CCDs),micromachines, DNA chips, and the like. Further, the present inventioncan be applied not only to an exposure apparatus for producingmicrodevices such as semiconductor devices, but can also be applied toan exposure apparatus that transfers a circuit pattern onto a glassplate or silicon wafer to produce a mask or reticle used in a lightexposure apparatus, an EUV exposure apparatus, an X-ray exposureapparatus, an electron-beam exposure apparatus, and the like.

Electronic devices such as semiconductor devices are manufacturedthrough the steps of; a step where the function/performance design ofthe device is performed, a step where a reticle based on the design stepis manufactured, a step where a wafer is manufactured from siliconmaterials, a lithography step where the pattern of a reticle istransferred onto the wafer by the exposure apparatus (pattern formationapparatus) in the embodiment previously described, a development stepwhere the wafer that has been exposed is developed, an etching stepwhere an exposed member of an area other than the area where the resistremains is removed by etching, a resist removing step where the resistthat is no longer necessary when etching has been completed is removed,a device assembly step (including a dicing process, a bonding process,the package process), inspection steps and the like. In this case, inthe lithography step, because the device pattern is formed on the waferby executing the exposure method previously described using the exposureapparatus of the embodiment, a highly integrated device can be producedwith good productivity.

While the above-described embodiments of the present invention are thepresently preferred embodiments thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

What is claimed is:
 1. A movable body apparatus including a movable bodywhich substantially moves along a predetermined plane and is movable toa predetermined position within the predetermined plane, the apparatuscomprising: a scale which is arranged at one of the movable body and anoutside of the movable body, with a first direction within a planeparallel to the predetermined plane serving as a longitudinal direction,the scale having a predetermined width in a second direction orthogonalto the first direction within the plane parallel to the predeterminedplane, the scale having a length extending in the first direction andhaving a width extending in the second direction, the length beingsubstantially longer than the width; a measurement device having aplurality of sensors each of which measures positional information ofthe movable body in a periodic direction of the scale at a plurality ofmeasurement points placed on the scale within the width of the scale sothat of the plurality of measurement points, n (wherein, n is an integerof two or more) or more points are positioned within the predeterminedwidth of the scale, and when the movable body is at the predeterminedposition, n+1 or more of the plurality of measurement points arepositioned within the predetermined width of the scale; and a controllerwhich performs position control of the movable body, using, as primaryinformation, a first measurement information including measurementinformation at a first measurement point out of the n or moremeasurement points positioned within the predetermined width of thescale or the n+1 or more measurement points positioned within thepredetermined width of the scale when the movable body is located at thepredetermined position, wherein the controller switches measurementinformation to use as the primary information in position control of themovable body to a second measurement information including measurementinformation at a second measurement point different from the firstmeasurement point, when abnormality occurs, due to malfunction of one ofthe sensors, in the first measurement information at the firstmeasurement point positioned within the predetermined width of thescale.
 2. The movable body apparatus according to claim 1 wherein thescale is arranged on a surface substantially parallel to thepredetermined plane of the movable body.
 3. The movable body apparatusaccording to claim 2 wherein on the movable body, the scale is arrangedin a pair separated from each other in the second direction, and themeasurement points are placed so that n or more measurement points areconstantly positioned in at least one of the pair of scales when themovable body is in a predetermined range within the predetermined plane.4. The movable body apparatus according to claim 2 wherein on themovable body, another pair of scales is further arranged with each ofthe longitudinal directions being the second direction, the another pairof scales being separated from each other in the first direction,wherein the measurement points are placed so that n or more measurementpoints are constantly positioned in at least one of the another pair ofscales when the movable body is in a predetermined range within thepredetermined plane.
 5. The movable body apparatus according to claim 1wherein each of the first measurement information and the secondmeasurement information includes measurement information at a pluralityof measurement points.
 6. The movable body apparatus according to claim1 wherein each of the first measurement information and the secondmeasurement information is measurement information at a singlemeasurement point.
 7. The movable body apparatus according to claim 1wherein each of the plurality of sensors has a head which irradiates ameasurement beam on a measurement point, and the controller performs theswitching when the abnormality in measurement information occurs due tomalfunction of one of the heads.
 8. The movable body apparatus accordingto claim 1 wherein each of the plurality of sensors has a head whichirradiates a measurement beam on a measurement point, and a plurality ofthe heads irradiate the measurement beams on different measurementpoints, respectively.
 9. The movable body apparatus according to claim 1wherein the measurement points are substantially equally spaced fromeach other in a direction orthogonal to the longitudinal direction ofthe scale by half or less than half of the predetermined width of thescale.
 10. The movable body apparatus according to claim 1 wherein themeasurement device has a first head and a second head which irradiatemeasurement beams on a same measurement point, and an irradiation areaof the measurement beam irradiated from the first head is in proximitywith an irradiation area of the measurement beam irradiated by thesecond head, without overlapping.
 11. A pattern formation apparatus thatforms a pattern on an object, the apparatus comprising: a patterningdevice which forms a pattern on the object, and the movable bodyapparatus according to claim 1 in which the object is mounted on themovable body.
 12. The pattern formation apparatus according to claim 11wherein the object has a sensitive layer, and the patterning deviceforms a pattern on the object by exposing the sensitive layer.
 13. Anexposure apparatus that forms a pattern on an object by irradiating anenergy beam, the apparatus comprising: a patterning device thatirradiates the energy beam on the object; the movable body apparatusaccording to claim 1 in which the object is mounted on the movable body,and a drive device which drives the movable body to make the objectrelatively move with respect to the energy beam.
 14. A devicemanufacturing method comprising: exposing an object with the exposureapparatus according to claim 13; and developing the exposed object. 15.A movable body apparatus including a movable body which substantiallymoves along a predetermined plane, the apparatus comprising: a scalewhich is arranged at one of the movable body and an outside of themovable body, with a first direction within a plane parallel to thepredetermined plane serving as a longitudinal direction, the scalehaving a predetermined width in a second direction orthogonal to thefirst direction within the plane parallel to the predetermined plane; ameasurement device which measures positional information of the movablebody in a periodic direction of the scale at a plurality of measurementpoints placed on the scale, the measurement device having a plurality ofhead sets each of which includes a first head that receives a firstpositional information of a first measurement point and a second headthat receives a second positional information of a second measurementpoint within a predetermined distance of the first measurement point,the predetermined distance being less than one-half the predeterminedwidth of the scale; and a controller which controls a position of themovable body using, as primary information, measurement informationgenerated by the first head, and switches the measurement informationused as the primary information from the measurement informationgenerated by the first head to measurement information generated by thesecond head when abnormality occurs in the measurement informationgenerated by the first head due to malfunction of the measurementdevice.
 16. The movable body apparatus according to claim 15 wherein thescale is arranged on a surface substantially parallel to thepredetermined plane of the movable body.
 17. The movable body apparatusaccording to claim 15 wherein the first measurement points, or the firstand second measurement points, on which the measurement beams arerespectively irradiated by the first heads and the second heads includedin the plurality of head sets, respectively, are substantially equallyspaced by the predetermined width.
 18. The movable body apparatusaccording to claim 15 wherein in the measurement device, at least a partof a measurement area where the measurement beam of the first headirradiates overlaps a part of a measurement area where the measurementbeam of the second head irradiates in parallel.
 19. The movable bodyapparatus according to claim 15 wherein the controller performs theswitching when the abnormality in measurement information occurs due tomalfunction of the first head.
 20. A pattern formation apparatus thatforms a pattern on an object, the apparatus comprising: a patterningdevice which forms a pattern on the object, and the movable bodyapparatus according to claim 15 in which the object is mounted on themovable body.
 21. The pattern formation apparatus according to claim 20wherein the object has a sensitive layer, and the patterning deviceforms a pattern on the object by exposing the sensitive layer.
 22. Anexposure apparatus that forms a pattern on an object by irradiating anenergy beam, the apparatus comprising: a patterning device thatirradiates the energy beam on the object; the movable body apparatusaccording to claim 15 in which the object is mounted on the movablebody, and a drive device which drives the movable body to make theobject relatively move with respect to the energy beam.
 23. A devicemanufacturing method comprising: exposing an object with the exposureapparatus according to claim 22; and developing the exposed object. 24.A movable body apparatus including a movable body which substantiallymoves along a predetermined plane, the apparatus comprising: ameasurement device which measures positional information of the movablebody in a direction of a single degree of freedom which is along thepredetermined plane, at a plurality of measurement points of the movablebody placed in a movement range of the movable body, wherein themeasurement device has a plurality of heads which simultaneouslygenerate respective measurement information on at least a same singlemeasurement point of the plurality of measurement points when themovable body is located at a predetermined position.
 25. The movablebody apparatus according to claim 24 wherein the plurality of heads areplaced at the movable body.
 26. The movable body apparatus according toclaim 24 wherein the movable body has a scale which reflects themeasurement beams irradiated from the plurality of heads.
 27. Themovable body apparatus according to claim 24 wherein the plurality ofheads include a first head and a second head which respectivelyirradiate measurement beams on the same single measurement point of theplurality of measurement points when the movable body is at thepredetermined position, and at the same single measurement point, atleast a part of an irradiation area of the measurement beam irradiatedfrom the first head overlaps at least a part of an irradiation area ofthe measurement beam simultaneously irradiated from the second head. 28.The movable body apparatus according to claim 24 wherein the pluralityof heads include a first head and a second head which respectivelyirradiate measurement beams on the same single measurement point of theplurality of measurement points when the movable body is at thepredetermined position, and the apparatus further comprises: acontroller which controls a position of the movable body using, asprimary information, measurement information generated by the first headof the plurality of heads irradiating measurement beams on the samesingle measurement point, and switches the measurement information usedas the primary information from the measurement information generated bythe first head to measurement information generated by the second headwhen abnormality occurs in the measurement information generated by thefirst head.
 29. The movable body apparatus according to claim 28 whereinthe controller performs the switching when the abnormality inmeasurement information occurs due to malfunction of the first head. 30.A pattern formation apparatus that forms a pattern on an object, theapparatus comprising: a patterning device which forms a pattern on theobject, and the movable body apparatus according to claim 24 in whichthe object is mounted on the movable body.
 31. The pattern formationapparatus according to claim 30 wherein the object has a sensitivelayer, and the patterning device forms a pattern on the object byexposing the sensitive layer.
 32. An exposure apparatus that forms apattern on an object by irradiating an energy beam, the apparatuscomprising: a patterning device that irradiates the energy beam on theobject; the movable body apparatus according to claim 24 in which theobject is mounted on the movable body, and a drive device which drivesthe movable body to make the object relatively move with respect to theenergy beam.
 33. A device manufacturing method comprising: exposing anobject with the exposure apparatus according to claim 32; and developingthe exposed object.